1. Field of the Invention
The present invention relates to an image forming system as a combination of an image forming apparatus and a peripheral device. For example, the invention relates to the control on a finishing device and an image forming apparatus.
2. Description of the Related Art
A finishing device of the above kind is to perform a finishing operation such as stapling and punching on a set of sheets or an individual sheet on which an image has been formed by an image forming apparatus. The image forming apparatus and the finishing device perform different kinds of processing and hence they are sometimes different from each other in productivity. As disclosed in JP-B-5-41991, an image forming system is known in which the productivity of the finishing device increased by providing plural compiler trays for setting processing and using the compiler trays cyclically (or alternately). Even if the productivity of the finishing device is increased in this manner, it is difficult to equalize it with the productivity of the image forming apparatus. In general, the image forming apparatus has higher productivity than the finishing device. If this is the case, time-related restrictions occur to enable a finishing operation; for example, to secure proper operation of the finishing device, the interval of an image forming operation of the image forming apparatus is adjusted.
However, since the restrictive conditions of the finishing device are not fixed, it is necessary to change an image forming operation of the image forming apparatus in accordance with the restrictive conditions of the finishing device. Several inventions and proposals have been made to avoid such restrictions. For example, JP-UM-A-1-159664 discloses a technique that the number of sheets that are fed to a finishing device is counted, and if the count exceeds the number of sheets of a set, the inter-set waiting time in an image forming operation of an image forming apparatus is elongated because the finishing operation should take a long time in this case. In this conventional example, the inter-set waiting time is set originally in the image forming apparatus. It is therefore necessary to change setting of the image forming apparatus if the finishing device is switched. This publication discloses only adjusting the waiting time of an image forming operation on the basis of the one restrictive condition, that is, the number of sheets for one kind of finishing operation; no consideration is given to a case involving plural restrictive conditions.
JP-A-11-208979 discloses a technique that a processing time necessary for a finishing operation on one set is acquired from a finishing device at the time of power application and the sheet feed interval is adjusted in accordance with the acquired processing time. According to this conventional example, since a processing time necessary for the finishing operation is acquired from the finishing device, adaptation to a new finishing device can be made by acquiring a processing time necessary for it even when the finishing operation is changed. However, this publication discloses only acquiring a processing time of inter-set processing from the finishing device at the time of power application, and gives no disclosures as to how to deal with a case in which an image formation processing interval other than the inter-process interval is necessary such as a case in which the image forming apparatus has a shorter sheet processing interval than the finishing device. Further, the only restrictive condition that is described in this publication is the one relating to stapling.
Finishing devices are now required to have an increasingly large number of functions such as stapling, punching, binding, and folding and the number of restrictive conditions is increasing accordingly. The number of combinations of restrictive conditions will become enormous. Therefore, it is becoming difficult to give, originally or in response to a notice that is supplied at the time of power application, an image forming apparatus information that enables it to manage even a combination of restrictive conditions as in the above conventional examples. This situation, which has been described above in connection with finishing devices, is also true of combinations of an image forming apparatus and peripheral devices such as a document reading device and a sheet feeder.
The present invention has been made in view of the above circumstances, and provides a system capable of flexibly adapting to various restrictive conditions resulting from a difference in productivity between an image forming apparatus and a peripheral device so as to enable maximum use of the productivity of each.
Therefore, according to the invention, in contrast to the conventional case in which the judgment and management relating to a restriction resulting from the peripheral device are performed by the image forming apparatus, the judgment and management relating to a restriction resulting from the peripheral device are performed by the peripheral device itself. Control is performed in such a manner that the peripheral device and the image forming apparatus communicate with each other.
More specifically, the image forming apparatus notifies, to the peripheral device, information that is necessary for the peripheral device to perform a processing control. The peripheral device generates information relating to a processing time that is necessary in the peripheral device on the basis of the received information, and notifies the generated information to the image forming apparatus. The image forming apparatus performs scheduling of its image forming operation on the basis of the received information relating to the processing time.